2600 stickers are in 3 bags.
The 1st bag has 200 stickers more than the total number of stickers in the 2nd and 3rd bags.
The 3rd bag has 2 times as many stickers as the 2nd bag.
How many stickers does the 1st bag contain?
Choose the bag with the least stickers to be 1 u.

Number of stickers in the 2nd bag = 1 u
Number of stickers in the 3rd bag = 2 u

Number of stickers in the 2nd bag and 3rd bag
= 1 u + 2 u
= 3 u

Number of stickers in the 1st bag = 3 u + 200

Total number of stickers
= 1 u + 2 u + 3 u + 200
= 6 u + 200

6 u + 200 = 2600
6 u = 2600 - 200
6 u = 2400

1 u = 2400 ÷ 6 = 400

Number of stickers in the 1st bag
= 3 u + 200
= 3 x 400 + 200
= 1200 + 200
= 1400

Answer(s): 1400